PostgreSQL and Trying to connect using Qt

clochydd

It is not necessary to compile postgresql, I used the binaries 32-bit and with installing ./lib and ./include had been provided, too.
Your make does not recognise the psql includes (the stuff, that follows -I) and that's why you still receive the message 'libpq-fe.h not found'.
Do you see the same error if you use backslashed paths with you qmake command? Qt uses forward slashes but I had success with the backslashed command.

SGaist

Just to be sure, wouldn't by any chance libpq-fe.h be in include/libpq ? If so it's that last element that was missing.

clochydd

Yes, this has been installed in "C:\Program Files (x86)\PostgreSQL\9.3\include" together with the binaries of PostgeSQL 32-bit:
"03.12.2013 06:13 21.082 libpq-fe.h"
and - the PostgreSQl include has to be added to qmake!

SGaist

Indeed, but you need to give the full path to libqp-fe.h not just the path that contains the libpq folder.

Please avoid having spaces in your path when developing, it something that is not working very well on windows

aftertaf

on my system i installed postgreSQL x86 9.3 to c:\psql93_x86\

so... the qmake command where i specify the INCLUDE+=, LIBS+= etc . . .
i need to tell it precisely and exactly where libqp-fe.h is, including full path ?

how do I do that, i.e. what separator do i use to add more than one entry into the "INCLUDE+=" that i've already specified (using clochydd's tuto on page 2. .) ?

clochydd

Go to the Qt plugin source directory:
cd QT_SRC_PATH\src\plugins\sqldrivers\psql

Start building the plugins:
(Change this to your mingw32 path: C:\Qt\Qt5.2.0\5.2.0\mingw48_32\bin)
C:\Qt\Qt5.2.0\5.2.0\mingw48_32\bin\qmake “INCLUDEPATH+=c:\psql93_x86\include”
“LIBS+=c:\psql93_x86\lib\libpq.lib” psql.pro

SGaist

libpq-fe.h being in include/libpq

You should use

@“INCLUDEPATH+=c:/psql93_x86/include/libpq”@

aftertaf

same :(

clochydd

Don't give up - we will find a solution, hopefully!

Is the qmake error message concerning the libpq-fe.h exactly as before?
Could you please post the message again?
Could you post the directory list of c:\psql93_x86\include?

aftertaf

just tried making the odbc driver again...
and get the Driver not Loaded message :)

C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>c:\Qt\5.2.1\mingw48_32\bin\qm
ake.exe "INCLUDEPATH+=c:/psql93_x86/include/libpq" "LIBS+=c:/psql93_x86/lib/libp
q.lib" psql.pro

C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>mingw32-make debug
mingw32-make -f Makefile.Debug
mingw32-make[1]: Entering directory 'C:/QT/5.2.1/Src/qtbase/src/plugins/sqldrive
rs/psql'
g++ -c -pipe -fno-keep-inline-dllexport -g -std=c++0x -fno-exceptions -frtti -Wa
ll -Wextra -DUNICODE -DQT_NO_CAST_TO_ASCII -DQT_NO_CAST_FROM_ASCII -DQT_NO_EXCEP
TIONS -DQT_PLUGIN -DQT_SQL_LIB -DQT_CORE_LIB -I. -I"C:\Qt\5.2.1\mingw48_32\inclu
de\QtSql\5.2.1" -I"C:\Qt\5.2.1\mingw48_32\include\QtSql\5.2.1\QtSql" -I"C:\Qt\5.
2.1\mingw48_32\include" -I"C:\Qt\5.2.1\mingw48_32\include\QtSql" -I"C:\Qt\5.2.1
mingw48_32\include\QtCore\5.2.1" -I"C:\Qt\5.2.1\mingw48_32\include\QtCore\5.2.1
QtCore" -I"C:\Qt\5.2.1\mingw48_32\include\QtCore" -I".moc\debug" -I"........
mkspecs\win32-g++" -o .obj\debug\qsql_psql.o ......\sql\drivers\psql\qsql_psql
.cpp
......\sql\drivers\psql\qsql_psql.cpp:59:22: fatal error: libpq-fe.h: No such
file or directory
#include <libpq-fe.h>
^
compilation terminated.
Makefile.Debug:497: recipe for target '.obj/debug/qsql_psql.o' failed
mingw32-make[1]: *** [.obj/debug/qsql_psql.o] Error 1
mingw32-make[1]: Leaving directory 'C:/QT/5.2.1/Src/qtbase/src/plugins/sqldriver
s/psql'
makefile:48: recipe for target 'debug' failed
mingw32-make: *** [debug] Error 2

aftertaf

http://pastebin.com/4cpqVMiN
folder contents

clochydd

Thanks for the data! I can see our "fatal" libpq-fe.h in c:\psql93_x86\include. So as a first step I suppose to test with:
C:\QT\5.2.1\Src\qtbase\src\plugins\sqldrivers\psql>c:\Qt\5.2.1\mingw48_32\bin\qmake.exe “INCLUDEPATH+=c:\psql93_x86\include” “LIBS+=c:\psql93_x86\lib\libpq.lib” psql.pro
I know, the backslashes are a bit unusual for Qt but it worked with my installs so give it a try! Good luck!

aftertaf

i've tried on many occasions with \ and /: same result.

The problem is obviously over my level of unkludging, and I've figured out how to use ODBC instead.

@
#include <QtSql>
#include <QString>
#include <QSqlDatabase>

void connect_db()
{

QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
QStringList driversList = QSqlDatabase::drivers();
qDebug() << "drivers list= " << driversList;
bool bOpen(false);
db.addDatabase("QODBC","odbcname");
db.setHostName("localhost");
db.setDatabaseName("dbname_in_postgres");
db.setUserName("username");
db.setPassword("password");
bOpen =db.open();
QString str=db.lastError().text();
}@

str remains empty :)
and bOpen shows True for the first time in a month's trying.
I dont need pure pg connection, using an ODBC is fine for me at this stage.
Now for trying to make my DAO classes :)
thanks to all for helping, sorry it didn't work out as intended, but for ODBC connections, my above code works.

Duncan

Hello!

What did you put for this line:

db.addDatabase("QODBC","odbcname");

Not sure what to put instead of odbcname.

Thanks!

clochydd

Hello Duncan,

if you only open one database, you do not need to specify the connection name:

db.addDatabase("QODBC");

If you plan work with more connections, use a name to identify each connection:

db.addDatabase("QODBC","myConn1");

SGaist

Hi,

addDatabase is a static function that returns a QSqlDatabase instance that will use the selected backend.

So you must call it like that:
QSqlDatabase db = QSqlDatabase::addDatabase("QODBC")

The suggestion of @clochydd about the connection name still applies.